With the rapid development of the express industry, a large number of packaging cases are used. A serious problem presented is that the packaging cases have poor packaging strength and security. A top plate and a bottom plate of one packaging case each have only one layer of case plate structure, especially, almost all of the conventional packaging cases have one layer of folded bottom cover structure, thus, the packaging case is easy to crack in the carrying, and the goods within the packaging case can be easily stolen through the bottom plate. That is to say, the structures of the bottom plate of the conventional packaging case have no anti-theft measures. Moreover, the overall structure of the packaging case causes poor performance in withstanding compression, damage and the like. Furthermore, the conventional packaging case is sealed by tapes, and in the express delivery process, someone can peel off the tapes on a packaging case, steal the goods in the packaging case, and then seal the packaging case with tapes as before, which can hardly be identified by the recipient, causing extremely poor security. Moreover, it needs scissors and other tools to open the packaging case, which is extremely inconvenient, and the use of tapes causes a large waste of packaging materials.